Hypertensive disorders of pregnancy — structured SAQ (15 marks)

(a) Classification and why the label is provisional (3 marks)

One mark for correct application of ISSHP 2021, one for naming the specific ambiguity, one for stating how it is resolved. [1]

• Apply ISSHP 2021 by timing first. Hypertension known before pregnancy or present before 20 weeks is chronic hypertension, white coat hypertension or masked hypertension. Hypertension arising at or after 20 weeks is transient gestational hypertension, gestational hypertension or preeclampsia.[1]
• She cannot be classified today because she has no reading before 20 weeks. She may have chronic hypertension only now detected, or genuinely new hypertension after 20 weeks.[1][6]
• State the mechanism of the trap: the physiological mid-second-trimester blood pressure nadir means even a documented normal reading at 18 to 20 weeks would not exclude chronic hypertension.[1][6]
• Resolution: the definitive label follows her postnatally — persistence of hypertension beyond 12 weeks postpartum reclassifies her as chronic hypertension. Manage her in the interim as if preeclampsia is possible.[1][2]

(b) Investigations today (4 marks)

Half a mark per correctly paired test and consequence, maximum four. [1][2]

Marks are lost for "routine bloods" without naming the thresholds, and for omitting the fetal assessment. [1]

(c) Pharmacological management and target (4 marks)

One mark for the correct agent with dose, one for titration, one for the target, one for the trial evidence. [2][4]

• First line: labetalol 100 to 200 mg orally twice daily, increased every two to three days to 200 to 400 mg two or three times daily, up to about 2,400 mg per day. Absolutely contraindicated in asthma.[2][3]
• Alternatives: nifedipine modified release 20 to 30 mg daily, titrated to 30 to 60 mg once or twice daily (up to about 120 mg per day); or methyldopa 250 mg two or three times daily, titrated to 500 to 750 mg three times daily (up to about 3 g per day), stopped postnatally because of depression risk.[2][6]
• Target: below 140/90 mmHg.[4]
• Evidence: CHAP randomised 2,408 women with mild chronic hypertension and showed that treating to below 140/90 mmHg reduced the composite of severe preeclampsia, indicated preterm birth before 35 weeks, abruption, or fetal or neonatal death from 37.0% to 30.2% (adjusted risk ratio 0.82) with no increase in small-for-gestational-age birth weight (11.2% versus 10.4%). CHIPS had earlier shown tight control was safe, with severe hypertension in 27.5% versus 40.6% with less-tight control.[4][5]
• Also state: aspirin should already be running for preeclampsia prophylaxis, and never prescribe an ACE inhibitor, angiotensin receptor blocker or atenolol.[6][2]

(d) The severe-range emergency at 31 weeks (4 marks)

One mark each for: urgency and time target with a named agent and dose; magnesium; investigations and fetal assessment; escalation, fluid and disposition. [3][7]

• Treat within 30 to 60 minutes of the confirmed severe reading. Choose from labetalol 10 to 20 mg intravenously over 2 minutes then 20 to 80 mg every 10 to 30 minutes to a cumulative maximum of 300 mg; hydralazine 5 to 10 mg intravenously over 2 minutes, repeated every 20 to 40 minutes to a cumulative 20 mg; or immediate-release nifedipine 10 to 20 mg orally repeated at 20 minutes. Target after treatment is roughly 130 to 150 systolic and 80 to 100 diastolic, avoiding a precipitous fall.[3]
• Magnesium sulfate 4 g intravenously over 15 to 20 minutes, then 1 g per hour for seizure prophylaxis — she has severe-range hypertension plus a neurological symptom. Magpie showed magnesium cut eclampsia by 58% (0.8% versus 1.9%).[7][2]
• Investigate and assess the fetus: full blood count, creatinine and electrolytes, liver enzymes, urate, protein:creatinine ratio, group and hold, coagulation if platelets are low; cardiotocography and ultrasound for growth, liquor and Doppler.[1][3]
• Escalate and support: admit, senior obstetrician and anaesthetist, restrict fluid to about 80 mL per hour, give betamethasone 11.4 mg intramuscularly with a second dose at 24 hours for fetal lung maturity, involve neonatology, and plan the timing of birth.[3][1]